Zipcar is the largest car share operator in the world, with more than 10,000 cars worldwide.

For the massive number of New Yorkers who don't own cars, making those quick trips where four wheels would be most convenient has been reinvented by car share services.

Quick rentals, by the hour or even by the day, provided by rental companies ranging from big names like Hertz and Enterprise to start-ups like Carpingo.

Enterprise CarShare and Carpingo both waive the first year annual fee for their lowest membership levels, while Zipcar charges a $60 annual fee. Hertz 24/7 has no annual fee and is the only one to not charge a $25 application fee.

For the most part, you pay an hourly rate—typically starting around $8 per hour—and they pick up the gas and insurance bill.

Until you cross the river.

New Yorkers who spend more of their time riding the rails than behind the wheel might be more familiar with Metrocard rates than toll prices.

Drivers crossing Port Authority bridges and tunnels, including the Lincoln and Holland tunnels as well as the George Washington Bridge, face a multi-tiered toll plan. E-ZPass tolls are either $8.25 or $10.25, depending on time of day, while those paying in cash face a $13 fee.

For car share drivers, it may be easy to assume that if gas and insurance are picked up, why not tolls? No operation is that generous, but how the toll bill is passed on varies from company to company.

Of the four car share companies contacted for this piece, all include E-ZPass transponders in their car. In the case of an off-peak trip over the George Washington Bridge, exactly how car share customers would see that $8.25 toll differs based on the provider.

"Our members would be charged the toll price that anyone with an E-ZPass would pay, not the cash toll price," a representative from Zipcar told the Daily News. That means the $8.25 toll would be paid by the customer with no added fees.

As for Enterprise CarShare, the E-ZPass rate is passed to customers, with an added 10% administration fee. "An admin fee on a toll of $8.25 would be about 83 cents," a rep for the company told us via email, leading to a total rate of $9.08.

Smaller car share Carpingo, which operates solely in Brooklyn and Queens, uses a base fee structure. Customers are passed along the toll at the cash rate as well as a $2.50 per day processing fee, meaning the $8.25 off-peak E-ZPass toll ends up being billed at $15.50.

Hertz 24/7, which is the most lenient when it comes to start-up fees, hits its drivers hardest on the tolls.

Using a third-party provider called PlatePass, Hertz passes along the full cash toll to its drivers, despite having an E-ZPass in the car. To add insult to injury, Hertz 24/7's website warns, "You will be charged a $4.95 service fee for each day of the rental."

That means the otherwise $8.25 off-peak E-ZPass rate could easily show up on the bill as $17.95.

Customers looking to forgo using car-share-issued E-ZPass transponders can still use their own. According to E-ZPass New York, even drivers who don't own cars can register for a transponder.

The E-ZPass New York Customer Service Center is in charge of electronic toll transponders for the New York State Thruway, Port Authority of New York and New Jersey, the New York State Bridge Authority, and MTA Bridges and Tunnels.

The Port Authority of New York & New Jersey charges a $1 monthly administrative fee for E-ZPass.